Reading Comprehension

PT157 · S4 · P3 · Q22 Definition of Species

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Political arguments about biodiversity and the preservation of endangered species generally assume we know what a species is.

Topic

The challenge and controversy of defining what counts as a "species," especially in ornithology, and the implications of different definitions.

Framework

Present Debate

Main Point

There is an ongoing debate among scientists about how to define a species, with significant practical and political consequences, especially for conservation. ( — opening sentences, and the summary of practical stakes at the end.)

P1: Debate Over What Constitutes a Species

This paragraph introduces the ongoing debate about what a "species" actually is, focusing on the classic divide between "lumpers" (who group similar populations) and "splitters" (who separate populations into more species). Lumpers use the biological species concept (reproductive isolation), while splitters prefer the phylogenetic species concept (diagnosable populations with unique, genetically traceable traits).

P2: Example of a "Splitter" – Sibley's Contributions

Here we get an example in ornithology: Charles G. Sibley, a splitter, used DNA technology to challenge conventional classifications of bird species, arguing for unexpected relationships among birds (like American vultures being closer to storks than to other vultures).

P3: Pushback and the Limits of Classification

Sibley's ideas faced significant criticism. A critic argues that interpreting genetic differences is arbitrary, and even Sibley concedes that species definitions are inherently slippery because many populations don’t fit our tidy definitions.

22.

Which one of the following, if true, would provide the strongest support for the author's assertion in the final sentence of the passage about the effects of increasing the number of recognized species?

It is becoming increasingly difficult
No Impact
We're only analyzing how many species would "need" protection, not how many species would get international protection. So the fact that international wildlife agreements are increasingly tough has no bearing on what we're analyzing.
26% picked this
Increasing the number of species
No Impact
This is talking about avian vs. mammalian, but what we care about is protected vs. unprotected.
4% picked this
In disputes over protection of
No Impact
There's nothing in here that relates to our hypothetical New World in which we're increasing the number of species. This weak idea that economics often outweighs science isn't giving us any reason to believe that some of these "new" species would add to the list of protected species.
31% picked this
Advances in scientific techniques like
No Impact
There's nothing useful in here to justify the idea that, "If we have new species, we'll have new protected species." This answer seems to be trying to convince us that future science will favor the Splitters. But we're not trying to strengthen the idea that we will be increasing the number of species. In other words, we're not trying to strengthen the trigger idea of, "If we increase number, we'll increase number of protected species" We need to understand the connection. Why would a world where Splitters are favored and more species are named lead to more protected species?
13% picked this
Correct
Proponents of the phylogenetic species
Why this is right
The world in which we increase the number of species is the world in which Splitters win. They are proponents of the phylogenetic species concept. They would challenge the idea that existing species A should only be 1 species. They would argue that it should be split it up into three species, A1, A2, and A3. If they win, then we just increased the number of species. This answer is saying, if no biological pop ? Splitters are less likely is endangered to argue for a split And so by contrapositive, if Splitters are arguing ? the biological pop for a species to be split is endangered As we discussed in our evaluation, if we only split very populous species into multiple species, that wouldn't necessarily trigger the addition of any new protected species. For example, splitting Species A, which has 30,000 specimens, into three species each of 10,000 specimens, would increase the number of species here from 1 to 3, but it wouldn't increase the number of protected species. A species with 30,000 or one with 10,000 is not endangered and thus not protected. This answer is saying that the Splitters usually wouldn't be going after a robust species like this. When they bother to challenge a classification and they try to get it subdivided into multiple species, the species they're challenging is an endangered one. They think Species B, which has 90 members, should really be B1, B2, and B3, and since B already had a low enough population to be protected, its subdivisions B1, B2, and B3 will certainly be low enough to be protected. When you "Split" a protected/endangered species, you get multiple protected/endangered species. So this answer choice strengthens the last sentence by assuring us that Splitters would be attempting to split up protected/endangered species.
Skill tested: Strengthen · how this choice captures the passage's function is the move to repeat next time.
27% picked this

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